(1aR,3aS,9cS,9dR,11aR,11bR)-7,8-dimethoxy-13-methyl-1a,2,3a,4,9c,9d,11,11a-octahydro-5H,10H-9b,11b-(ethanoiminomethano)-1,3-dioxa-5a-azacyclopropa[4,5]cyclohepta[1,2,3-cd]fluoranthene-5,10-dione